1. Field of the Invention
The present invention relates to a server apparatus, a speaker device and a multi-speaker audio system. The present invention also relates to a layout configuration detection method of the speaker devices in the multi-speaker audio system.
2. Description of the Related Art
FIG. 61 shows a typical audio system in which a multi-channel acoustic field of a multi-channel signal such as 5.1-channel surround signal is produced using a plurality of speaker devices.
The audio system includes a multi-channel amplifier 1 and a plurality of speaker devices 2 of the number equal to the number of channels. The 5.1-channel surround signals include signals of a left (L) channel, a right (R) channel, a center channel, a left-surround (LS) channel, a right-surround (RS) channel, and a low-frequency effect (LFE) channel. If all channels are used for playing, six speakers are required. The six speakers are arranged with respect to the forward direction of a listener so that the sound images of sounds emitted from respective channels are localized at respective intended locations.
A multi-channel amplifier 1 includes a channel decoder 3, and a plurality of audio amplifiers 4 of the number equal to the number of channels. The output terminals of the audio amplifiers 4 are connected to respective output terminals (speaker connection terminals) 5 of the number equal to the number of channels.
The 5.1-channel surround signal input to the input terminal 6 is decomposed into the audio channel signals by the channel decoder 3. The audio channel signals from the channel decoder 3 are supplied to the speakers 2 via the audio amplifiers 4 and then the output terminals 5. Each channel sound is thus emitted from the respective speaker device 2. Volume control and audio effect process are not shown in FIG. 6.
To listen to a two-channel source in the 5.1-channel surround audio system of FIG. 61, only both a left channel and a right channel are used, with the remaining four channels unused.
To listen to a multi-channel source such as a 6.1-channel source or a 7.1-channel source, the system reduces the number of output channels to the 5.1-channel surround signal using a down-mix process. The number of speaker connection terminals is smaller than the number of channels, even if the channel decoder 3 has a capability to extract required audio signals from the multi channels. The down-mix process is performed to work as the 5.1-channel surround signal.
FIG. 62 illustrates a speaker device that is designed to be connected to a personal computer. The speaker device is commercially available in a pair of an L-channel module 7L and a R-channel module 7R.
As shown in FIG. 62, the L-channel module 7L includes a channel decoder 8, an audio amplifier 9L, an L-channel speaker 10L, and an input terminal 11 to be connected to a universal serial bus (USB) terminal of the personal computer. The R-channel module 7R includes an audio amplifier 9R that is connected to an R-channel audio signal output terminal of the channel decoder 8 in the L-channel module 7L via a connection cable 12, and an R-channel speaker 10R.
An audio signal in a format containing L/R channel signals is output from the USB terminal of the personal computer and then input to the channel decoder 8 in the L-channel module 7L via the input terminal 11. The channel decoder 8 outputs an L-channel audio signal and an R-channel audio signal in response to the input signal.
The L-channel audio signal from the channel decoder 8 is supplied to the L-channel speaker 10L via the audio amplifier 9L for playing. The R-channel audio signal from the channel decoder 8 is supplied to the audio amplifier 9R in the R-channel module 7R via the connection cable 12. The R-channel audio signal is then supplied to the R-channel speaker 10R via the audio amplifier 9R.
Japanese Unexamined Patent Application Publication No. 2002-199500 discloses a virtual sound image localization processor in a 5.1-channel surround audio system. The virtual sound image localization processor modifies a virtual sound image location to a modified sound image location when a user instructs the processor to modify a sound image. In other words, the disclosed audio system performs sound playing corresponding to a “multi-angle function” that is one of features of DVD video disks.
The multi-angle function allows a user to switch a camera angle to a maximum of nine angles up to the user's preference. Pictures of movie scene, sporting events, live events, etc. are taken at a plurality of camera angles and stored on a video disk, and the user is free to select any one of the cameral angles.
Each of the plurality of speaker devices is provided with a multi-channel audio signal that is appropriately channel synthesized. In response to an angle mode selected by a user, a channel synthesis ratio is updated and controlled so that each sound image is properly localized. In accordance with the disclosed technique, the user achieves sound playing at a sound image localized in accordance with the selected angle mode.
The audio system of FIG. 62 is an L/R two channel system. To work with a multi-channel source, a new audio system must be newly purchased.
In the known arts of FIGS. 61 and 62, the channel decoders 3 and 8 work with a fixed multi-channel input signal and fixed decomposed output channels as stated in the specifications thereof. This arrangement inconveniences the user, because the user can neither increase the number of speakers, nor rearrange the layout of the speaker device to any desired one.
In view of this point, the disclosed virtual sound image location process technique can provide an audio system that permits a desired sound image localization even when speakers of any number is arranged at any desired locations.
More specifically, the number of speakers is entered and the information of the speaker layout is entered in the audio system, and the layout configuration of the speakers of the audio system with respect to a listener is identified. If the speaker layout configuration is identified, a channel synthesis ratio of the audio signal to be supplied to each speaker is calculated. The audio system thus achieves a desired sound localization even if speakers of any number are arranged at any locations.
The disclosed technique is not limited to the channel synthesis of multi-channel audio signals. For example, the audio system generates signals to be supplied to a plurality of speakers more than the number of channels of a sound source, from the source sound, such as a monophonic audio signal or a sound source having a smaller number of channels, by setting a channel synthesis ratio. The audio system thus generates a pseudo-plural channel sound image.
If the number of speakers and the layout configuration of the speakers are identified in the audio system, a desired sound image is produced in the audio system by setting a channel coding radio and a channel decoding ratio in accordance with a speaker layout configuration.
However, it is difficult for a listener to enter accurate speaker layout information in the audio system. When the speaker layout is modified, new speaker layout information must be entered. This inconveniences the user. The speaker layout configuration is preferably entered in an automatic fashion.